GATEWAY, Colo. (CBS4) – Two large pot growing sites have been discovered on land that belongs to the Bureau of Land Management in Colorado.

Officials with the U.S. Department of Justice released information about the grows, both of which were busted last month.

READ MORE: Blue Angels Jet Makes Emergency Landing At Great Colorado Air Show

People spotted the grows and led rangers to the sites in Montrose County, south of the town of Gateway. Investigators say each site had thousands of plants.

Authorities busted four people at one of the grows. Six were arrested at the second site.

READ MORE: Marijuana Social Equity Fair Seeks To Level The Playing Field For Communities Of Color

(credit: Bureau of Land Management)

(credit: Bureau of Land Management)

Investigators say the grows are unrelated.

MORE NEWS: Hikers Discouraged From Climbing Kit Carson Peak As Madeline Baharlou-Quivey's Body Recovered

“Illicit marijuana grows on public lands violate the drug laws and harm the environment,” said U.S. Attorney John Walsh in a statement. “This Fall, Colorado has seen an explosion in the number and size of illicit marijuana grows on public land, which federal and state authorities are aggressively investigating and prosecuting.”